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Large and Long Programs (LLP)

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Proposals for Gemini Observatory Large and Long Programs (LLPs) are accepted annually, with a Call for Letters of Intent to Propose issued in early December of the year preceding the start of the new programs.  New LLP proposals are now solicited for 2024. Letters of intent to propose are due on February 12, 9am HST, 2024. UPDATE: with the added availability of MAROON-X (for 5 semesters) at Gemini North, the deadline for LoI has been extended to February 20, 9am HST. More information if given in the 2024 Call.

Large and long programs (hereafter "large programs" or LLPs) are Principal Investigator-defined and -driven programs that, as a guideline, either require significantly more time than a partner typically approves for a single program or extend over two to six semesters, or both. Large programs are expected to promote collaborations, to have significant scientific impact, and normally to provide a homogeneous data set, potentially for more general use. Proposals for Large and Long programs will usually be accepted annually.

The participating partners (currently US and Canada) will make available up to 20% of their time at each Gemini telescope for LLPs, over each of the next 6 semesters from the start of LLP execution. Principal Investigators (PIs) of LLPs must be based in an institution of one of the participating partner countries. There is no restriction on Co-Investigators. The LLPs are designed to enable large programs and/or programs running across multiple semesters to be reviewed within a single time allocation process.

PIs who propose for LLPs have additional requirements, including submission of a letter of intent, development of a management and data plan, and consideration of added value to the astronomical community through data products, software, or other outcomes. Successful PIs must additionally report on their progress annually. Beginning with newly accepted LLPs in 2018, each program will be required to deliver processed data within one year of the end of the original LLP term, to be hosted on the Gemini Observatory Archive.

Subaru Intensive Program (SIP) time is available via the LLP process.

Questions and Answers

All questions concerning proposals, or any other subject, should be made using the Gemini HelpDesk. This web-based system will send the request to your National Gemini Office staff in the first instance who will then escalate it to Gemini staff if necessary.


The Large and Long Program Proposal Process

This page describes the general Large and Long Program (LLP) proposal process. Additional details pertaining to a specific call for proposals can be found on the current Call for Proposals.


Letters of Intent

Letters of Intent to propose an LLP must be received by email to typically in early February of the cycle year. Letters must include the following information, in the order listed:

  • Title of Project
  • PI with full name of institution and contact information (phone and email)
  • Co-Is with full names of institution
  • Broad scientific overview of the program (500 word limit)

The Letters of Intent enable the selection of an allocation committee with minimal conflict of interest and applicable scientific expertise. Secondly, the description of the proposal program will allow for a review of the program in light of technical and operational constraints. Please keep this in mind when composing a Letter of Intent to ensure that relevant material is included.


Proposals for LLPs are typically due around April 1 of the cycle year. Investigators must use the Gemini Phase I Tool for creating and submitting LLP proposals. A new Phase I Tool (PIT) is released each semester. Information on how to download and install the Tool is given on the semester's installation page. Help on the PIT is available via the PIT help page and video tutorials. Information on target restrictions, instrument availability, and time availability is given in the current LLP Call For Proposals. Templates for the narrative, to be attached as two pdf files, are given for each semester. The LLP template (NOT the regular proposal template) must be used. The total time requested must include all overheads and calibrations. Each Gemini instrument web page includes information on overheads (under proposal preparation) and calibration.

Large and Long Proposals are subject to a Dual Anonymous Review Process (DARP). The pdf attachments consist of an anonymized Science Case and a separate attachment giving the team background. The team information is reviewed by the Committee after the initial science ranking. All parts of the LLP proposal, except for the team background in the second attachment, must be anonymized. A proposal that is not anonymized will be penalized. The Science Case includes a section on the Management Plan; in an anonymized way, this should describe the overall plan for conducting the program, including:

  • Approach: Discuss the organizational plan to execute the tasks required to complete the research goals and delivery of the data products. This discussion should include plans to support the observing runs, the pipeline processing plan, data reduction and analysis, archiving plan, data dissemination plan, and coordination of the survey with non-NOIRLab facilities or data sources.
  • Personnel requirements without naming specific people: Discuss the roles needed that are relevant to management and data release, including anticipated levels of work. Specific team members should NOT be named in this part of the proposal, only key roles and work to be done. Identifying information should be saved for the Team Background section of the proposal, in the second attachment.

Describe the data products (reduced observations, single or stacked images, spectra, object catalogs, and so on) to be released, as well as the timeline and mechanism of their release to the community. Please differentiate between intermediate products developed during the execution of the survey and the final products likely to be produced after the full observations have been obtained.

The science case must also include:

  • a discussion of the primary scientific justification of the project;
  • a description of the experimental design, including sample selection, scheduling requirements, calibration, etc.;
  • a statement of the time requested each semester, including required instruments and observing conditions in the technical case;
  • a description of the mode of observation;
  • program considerations if allocated in band 2, included in the experimental design;
  • a discussion on added value to Gemini Observatory and the broader astronomical communities through the public release of data products, catalogs, software, public outreach, or other outcomes beyond the proposed science results;
  • an estimate of the distribution of targets and time allocation throughout the lifetime of the proposed LLP;
  • sample, relevant Integration Time Calculator (ITC) output supporting time request.

Other required information, entered directly into the PIT:

  • title, abstract, TAC category, keywords, and the investigators' names and institutions;
  • a list of targets, observing conditions, and instrument configurations for the first semester;
  • scheduling constraints if there are time-critical or synchronous observations involved.

The science case and the team background attachments together are limited to a total of 10 pages; the science justification cannot exceed 5 pages, including figures and references. The page limit does not include ITC attachments or the distribution of targets table.

Proposal Evaluation and Acceptance

A separate Large Program Time Allocation Committee (LPTAC) will evaluate the submitted LLP proposals, assessing them for scientific excellence and program feasibility, including program management. While membership in the LPTAC is selected, in part, to provide expertise on the science cases as indicated in the Letters of Intent, LLP proposal science justifications should be intelligible to a broad audience. The LPTAC will base their evaluations of proposals on the criteria listed here in descending order of importance.

  1. The overall scientific merit of the proposed investigation and its potential contribution to the advancement of scientific knowledge.
  2. The technical feasibility of the proposed observations.
  3. The ability of the proposing team to carry out the proposed research to a successful conclusion within the proposed timeframe, as established by the management plan.
  4. Added value to the Gemini and broader astronomical communities beyond LLP team science results, as demonstrated by the planned public release of reduced data products, catalogs, software, public outreach, or other outcomes.
  5. The extent to which the observations can be accommodated within routine Gemini operations and the extent to which the overall science program enables an efficient use of the observatory.

Following the LPTAC process, the LPTAC sends their recommendations to Gemini Observatory. While most proposals recommended by the TAC are allocated time, additional operational and scheduling constraints can prevent high-ranking programs from being awarded time. Successful LLPs will have the equivalent of either Band 1 or band 2 status. In general, a LLP will have the same band status throughout the lifetime of the LLP. However, some programs may have their allocations moved between bands during the life of the LLP, due to operational and time allocation constraints. Programs are made aware of the expected band status when the initial allocation is awarded. These bands have the same meaning and expectations of completion as regular queue programs. Successful and unsuccessful LLP proposal PIs will receive LPTAC feedback and scoring information after the LPTAC and telescope scheduling process.

Time Allocations

LLPs can have allocations spanning more than a single semester and an expected amount of time allocated within a given semester. Each semester, during the ITAC process, LLPs expected allocations are required to be merged with regular queue programs, classical requests, limited-term partnerships, etc., in the telescope scheduling process. Some changes to semester allocations may result from this merge process.

LLP programs do not have rollover status. Although a program may continue from one semester into the next, any remaining time on the program from the previous semester will be lost. The PI can request adjustments through their annual reporting cycle, but for our operational purposes time is not carried over semester boundaries and the program will commence with the "fresh" allocation of time at the start of each semester. Although time does not carry forward over a semester boundary, PIs can choose to execute observations not completed in the previous semester, "paid for" from their time allocation in the current semester.

Observing Modes

The Large Program PIs and Co-Is are encouraged to visit Gemini a) for Gemini to learn from them and to optimally support them, b) for them to learn about Gemini operations in order to optimally plan their observations and their data reduction, whatever mode of observation they are using. This is dependent on any travel and meeting restrictions that are in place.

Three modes of observations are normally available to LLPs:

Priority visiting observing : The PI or team member comes to Gemini, prepared to observe either their own program if the conditions are sufficiently good, or to execute approved queue programs if the conditions are too poor for the LLP. The LLP will be charged only for time devoted to the program, and additional observations may be made by Gemini staff or other observers of the queue during the semester. (See the PV Mode Definition page for more information). A Band 2 LLP must justify the need for this mode.

Queue: LLP observations are executed only as part of the regular queue, observed by Gemini staff or other observers. 

Classical: The program is scheduled on specific dates, and the PI or a team member comes to Gemini to observe that program on those dates, accepting the variability of weather.  A Band 2 LLP must justify the need for this mode.

If classical or priority visitor mode is selected, the LLP PI must certify that the visiting observers have sufficient observing experience to execute the program. Gemini staff will not provide basic training about observing techniques.

Additional Requirements on Large and Long Programs

Annual Progress Reports

Successful LLPs will require an annual program review, led by the LPTAC. Each LLP will submit an annual progress report containing (at a minimum) a summary of the observing time used thus far, comments on the quality of the data and whether the data quality is sufficient to meet the scientific goals of the program, a summary of the activities of each team member, the status of reduction of the data, and detailed plans for the next year of the project. The report should also indicate any science results arising from the project, whether published or in preparation. The committee's recommendation and Gemini Director's approval will be required before allocations for an ongoing LLP can continue.

Submission of Observation details

Successful LLPs will also be required to submit detailed target, observing constraint, and instrument configuration details in advance of each semester's ITAC process.

Requirement for the Delivery of Processed Data

Beginning with the 2018 LLP proposal cycle, all new large programs will be required to submit processed data to the Gemini Observatory Archive (GOA) within one year of the original planned end date of the program as stated in the proposal. The data will be required to be in the FITS format, and contain header metadata such that it is searchable within the GOA. Programs will also be required to submit documentation detailing the data reduction procedure and describing the data provided. The details of these requirements are available in this document. We encourage potential PIs with questions about this requirement to email

Final Program Review

Completed LLPs will also be required to submit a final program review.

Large and Long Program Completion Policy


  • “Term” is the initial allocation of semesters over which an LLP is to run.
  • “Completion” is the ratio of validated time to allocated time (to the whole program, for its whole term).


Band 1, non-ToO LLPs that fail to reach 80% completion by the end of their term will be extended on a semester-by-semester basis. The program execution will be stopped when 80% completion is reached. The PI may request further extension from the LPTAC during the annual review process. Band 2 programs, and Band 1 programs with 80 per cent or more completeness at the end of their term, may ask the LPTAC for extensions.


In its meeting of November 2017, the STAC discussed  completion policy for Large/Long Programs. Its recommendation was as follows:

STAC 13.11 A high level of completeness is needed to maximize the scientific return of Large and Long Programs. For future LLPs the STAC recommends a new policy on guaranteed completeness: we propose that Band 1 LLPs that reach the end of their term with <80 per cent of their allocated observations completed be automatically extended into future semesters until they reach at least 80 per cent completeness, provided the annual progress reports are satisfactory. The current policy that Band 2 programs and Band 1 programs with 80 per cent or more completeness may ask the LPTAC for extensions should be continued. 

Large and Long Programs - Frequently Asked Questions

1. What is the proprietary period for data obtained in a LLP?

Data obtained as part of an LLP shall have the standard proprietary period, 12 months from the date of an individual observation, although PIs are encouraged to consider a shorter proprietary period, or waiving it altogether.

2. Why is there a restriction on LLP PIs, leaving out astronomers from Brazil, Argentina, Korea, and Chile?

Brazil, Korea, Argentina, and Chile have elected not to participate in the Gemini Large and Long Program at this time, a decision confirmed at the Board level. University of Hawaii faculty can apply by using US (not UH) time.

3. Does a proposal need to have “added value” beyond the science results to be successful?

No, a successful proposal does not need to have added value beyond the scientific results.  This is merely one of the criteria by which all proposals will be judged (See Section 2.3).  A statement on added value, even if only to acknowledge there is none, is required by all proposals.

4. Will LLPs be subject to review by the National TAC of the PI?

No. LLP proposals will only be reviewed by the LPTAC. However, there may be overlap between a partner's National TAC and their representation on the LPTAC.

5. Who will select the members of the LPTAC?

The LPTAC will have 8 'partner' members, six from the US, and two from Canada.  These members are nominated by the corresponding designated Gemini Board members, or their delegates, and approved by the Gemini Director. Additional members may be appointed by the Observatory in order to balance the scientific expertise in the committee.  Any qualified, unconflicted scientist may serve in these 'at-large' positions; they do not need to come from the Gemini partnership or participating LLP partners.

6. What is the purpose of "considerations if allocated in band 2" requirement in the proposal narrative?

All awarded LLPs will be given allocations in either band 1 or 2. The expected completion rates are different in each band and PIs may wish to consider this impact upon a band 2 allocation. Possible considerations are a relaxing of the observing constraints and potential corresponding increase in allocation request, greater flexibility on targets and/or instrument configurations, or other consideration that would give greater flexibility in scheduling the science observations.

7. Are their supporting funds available from Gemini Observatory for successful LLPs?

No. Gemini will not offer supporting funds for LLPs.

8. Is the Target of Opportunity (ToO) observing mode available for LLPs?

Yes, PIs are welcome to propose LLPs using the ToO observing mode. The guidelines for ToO observations at Gemini Observatory will generally apply to LLPs using this mode. See also Question 9 for more information about submitting for ToO observing mode.

9. Can I submit a mix of Standard and Rapid ToO observations in the same LLP proposal?

Yes. If your proposal contains any Rapid ToO observations, submit your proposal as a Rapid ToO proposal, even if it also contains Standard ToO observations. If your proposal only contains Standard ToO observations, submit your proposal as a Standard ToO proposal. If different conditions are required for the Rapid and Standard ToO observations, they must all be specified using different observations using the appropriate observing constraints. Investigators should be clear in the proposals about the total time requested in Rapid and/or Standard ToO observing modes.

10. Can I change the co-I list from the original I submitted on my letter of intent?

Yes, you may adjust the co-I list. You do not need to inform Gemini of the change, just provide the complete and correct list with the final proposal submission.

11. Can I submit my program to both the LLP and regular semester Call for Proposals?

Yes. As the oversubscription rate for Large and Long Programs (LLPs) remains high, PIs are encouraged to consider proposing a subset of their LLP proposal as a regular semester proposal. PIs submitting proposals for the same science program to both the regular and LLP call for proposals are requested to indicate this in the "Use of Other Facilities or Resources” section of the regular queue proposal.

Policy for Participants Joining or Leaving the LLP Program


This policy determines how Gemini Participants (countries) may join or leave the LLP Program.  It was agreed by the Gemini Board of Directors at its May 2018 meeting. 


Participants may enter the LLP Program at any time as long as the first time requested is in a B Semester, at which time their queue allocations will be decreased by a maximum of 20% (this is a cap, not an absolute charge per Semester) until they exit.


Participants wishing to withdraw from the LLP program must declare their intention to do so at the final Board meeting in the year, and must confirm their withdrawal to the Observatory by the end of November. All LLPs led by that participant will cease as LLPs at the end of the next A semester. The exiting participant may choose to move uncompleted LLP programs into their regular queue allocation from the next B semester.

Large and Long Programs (LLP) | Gemini Observatory


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